PIPA Polyol Based Viscoelastic Foams

摘要

Viscoelastic foam is made by reacting an isocyanate compound with water and a polyol mixture. The polyol mixture contains a dispersion of polyurethane or polyurethane-urea particles in a carrier polyol (a PIPA polyol) and at least one other polyol that is a homopolymer of propylene oxide or a copolymer of 20 to 99.9 weight-% propylene oxide and 0.1 to 80 weight-% ethylene oxide, has 2 to 4 hydroxyl groups per molecule and has a hydroxyl equivalent weight of 200 to 400. The VE foams are characterized by high airflows and long recovery times.

主权项

1. A method of making a viscoelastic foam, comprising combining at least one organic polyisocyanate with water and a polyol mixture at an isocyanate index of 60 to 150 to form a reaction mixture and curing the reaction mixture to form a polyurethane-urea foam having a foam density of 30 to 120 kg/m3, a resiliency of less than 15% and a recovery time of at least 3 seconds, wherein the polyol mixture includes:
Polyol A: at least one dispersion of polyurethane and/or polyurethane-urea particles in a carrier polyol, wherein the carrier polyol has an average molecular weight of 600 to 5000 and an average of at least two hydroxyl groups per molecule, the dispersed polyurethane or polyurethane-urea particles constitute from 5 to 50 weight percent of the dispersion and the dispersion has a hydroxyl number of at least 40; and Polyol B: at least one polyol which is a homopolymer of propylene oxide or a copolymer of 20 to 99.9 weight-% propylene oxide and 0.1 to 80 weight-% ethylene oxide, has 2 to 4 hydroxyl groups per molecule and has a hydroxyl equivalent weight of 200 to 400; and further wherein Polyols A and B together constitute at least 75 weight-percent of all isocyanate-reactive materials other than water in the reaction mixture and the polyol mixture contains at least 1 weight-percent of the dispersed polyurethane or polyurethane-urea particles.